Co-precipitation Synthesis and Calcination-Tuned Properties of CdWO4 Nanoparticles for Efficient Photocatalytic Degradation of Methylene Blue

The effective removal of organic pollutants from wastewater demands advanced photocatalytic materials. In this study, we hypothesized that calcination temperature could strategically optimize the structural and optical properties of cadmium tungstate (CdWO4) nanoparticles to enhance their photocatalytic performance. CdWO4 nanoparticles were synthesized via a co-precipitation method and calcinated at temperatures ranging from 400 to 600 °C. Systematic characterization using X-ray diffraction confirmed the monoclinic phase, revealing that higher calcination temperatures increased the crystallite size and optical bandgap, while reducing the surface area. The CdWO₄ nanoparticles showed a progressive decrease in surface area from 9.1 to 1.5 m2/g, but an increase in optical band gap from 2.8 to 3.4 eV with an increase in the calcination temperature from 400 to 600 °C, demonstrating the interplay between textural and electronic properties in photocatalytic performance. Photocatalytic efficiency was evaluated through methylene blue (MB) degradation under UV-visible light, demonstrating a significant enhancement with increasing calcination temperature. The sample calcinated at 600 °C achieved 90.5% MB degradation and has a rate constant of 3.21 × 10− 3 min− 1, compared to 61.7% for the as-prepared sample. These improvements were attributed to superior crystallinity and charge separation obtained at elevated calcination temperatures. Furthermore, the high density and atomic number of tungsten in CdWO4 suggest its functionality for possible radiation shielding applications. Our findings highlight calcination as an effective strategy for tailoring CdWO4 nanoparticles for multifunctional environmental and protective applications.